Process and apparatus for the production of aerogeodetical stereophotographs



Ma V 1a ,1926, 1,585,484

M. GASSE PROCESS AND APPARATUS FOR THE PRODUCTION OF AEROGEODETICAL STEREOPHOTOGRAPHS Filed June 27, 1914 ll Sheets-Sheet 1 May M. GASSER PROCESS AND APPARATUS FOR THE PRODUCTION OF AEROGEODETICAL STEREOPHOTOGRAPHS Filed June 27, 1914 11 Sheets-Sheet 2 duos/7m? A74): 614 885R M. GASSER PROCESS AND APPARATUS FOR THE PRODUCTION OF AEROGEODETICAL STEREOPHOTOGRAPHS Filed June 27, 1914 ll Sheets-Sheet 5 May 18 1926.

1 M. GASSER PROCESS AND APPARATUS FOR THE PRODUCTION OF ABROGEODETIOAL STEREOPHOTOGRAPHS -11 Sheets-Sheet 4 Filed June 27, 1914' flax 6345551? 4rramvsy PROCESS AND APPARATUS FOR THE PRODUCTION OF AEROGEODETICAL STEREOPHOTOGRAPHS 11 Sheets-Sheet 5 Filed June 7, 1914 May 18,1926. 1,585,484

M. GASSER PROCESS AND APPARATUS FOR THE PRODUCTION OF AEROGEODETICAL STEREOPHOTOGRAPHS Filed June 1914 ll Sheets-Sheet 6 Awavroe MAX 6/1550? May 18 1926., 1,585,484

' M. GASSER PROCESS AND APPARATUS FOR THE PRODUCTION OF AEROGEODETICAL STEREOPHOTOGRAPHS Filed June 27, 1914 ll Sheets-Sheet 7 May 18, 1926. I 1,585,484

M GASSER PROCESS AND APPARATUS FOR THE PRODUCTION OF AEROGEODETICAL STEREOPHOTOGRAPHS Filed June 1914 ll Sheets-Sheet 8 Arron/vs Y May 8 1926. 1,585,484

- M. GASSER PROCESS AND APPARATUS FOR THE PRODUCTION OF AEROGEODETICAL STEREOPHOTOGRAPHS Filed June 27, 1914 ll Sheets-Sheet 9 M. GASSER May 18 1926.

PROCESS AND APPARATUS FOR THE PRODUCTION OF AEROGEODETICAL STEREOPHOTOGRAFHS Filed June 27, 19M 11 Sheets-Sheet 10 wil--- M W W MAX Asst-R M. GASSE R May 18 1926.

PROCESS AND APPARATUS FOR THE PRODUGTION OF AEROGEODETICAL STEREOPHOTOGRAPHS Filed June 2'7,v 1914 11 Sheets-Sheet 11 MM a Arm/Fan's) Patented May 18, 1926.-

UNITED STATES 1,585,484 PATENT OFFICE.

MAX GASSER, F DARMSTADT, GERMANY.

PROCESS AND APPARATUS FOR THE PRODUCTION OF AEROGEODETICAL STEREO- A PHOTOGRAPHS.

Application filed June 27, 1914. Serial No. 847,665.

(GRANTED UNDER THE PROVISIONS OF THE ACT OF MARCH 3,1921, 41 STAT. L., 1313.)

My invention relates to a method and apparatus for obtaining areo-geodetlcal stereophotographs.

Photographic pictures are made from an and in that further all the objectives are siimiltaneously opened by automatic means. The invention further consists in that the cameras only .then commence to act when the airship or the flying-machine comes into or swings through a horizontal line of flight andlinally, in that by means of two recording cameras the readings of all auxiliary appa1'atus,"sucli as clocks, ai'ieroids, spirit or water levels, surveying statl's, or the like are registered.

Stereo-photograimnetrical measurements from airships must be based upon quite new principles. On account of the above mentioned simultaneous bi-axial photography, stereo-pliotogrammetry permits of the plates, by means of the stereoscopic effect, being measured in the comparator or in a mechanical protracting instrument. With this process therefore, the relief of the landscape is seen in the comparator. A further advantage of stereo-photogrammetry' when compared with the earlier simple balloon-photography and its methods .of' estimation consists in that each photograph from each plate holder can be automatically estimated or valued in conjunction with the other plateholder in the pro- 4 tracting instrument.

A further advantage is that ;no mathen'iatical calculation is necessary and no rephotographing for estimating purposes, but the perspective of the photograph is'con verted by automatic means into the right angled co-ordinates of a topographical map of a kind now commonly employed, simply by bringing the comparator marks into coincidence with the similar (identical) picture points. llhcn compared withl' that which is known {upon the subject," the bi axial stere0 )hotogrammctrical"aero photography is to be regarded as the purpose of" the whole device and its employment for the purpose of making maps is likewise new.

The object of the invention is to obtain by means of the co-action of the technical detail, a syl'ichronous bi-axial acro-photograph which approaches as nearly as possible to the stereo-photogrammetrical normal case. The axis of the airship must consequently be horizontal at the moment of exposure, and the two camera axes must be vertical and adjusted with relation to each other in order .to give the stereophotogrammetrical normal case. Although the protracting apparatus permits of estimating and converting photographs .to maps, with inclined axes, the object is especially to obtain a normal case by the coaction of the manual and electro-mechanical devices. These devices comprise tensionin'g devices for the base, photographic apparatus with corresponding suspension devices, stabilizing and adjusting mechanism and finally, special devices for causing the simultaneous release of the operating parts.

()n the accompanying drawings devices are illustrated by way of example for carrying out the process for obtaining aeroggeodetical s tereophotographs.

Figs. 1 and 2 are side and bottom views respectively of a base tensioning device for keel ships. which is anti'imatically tautened by the weight of theobservation cabins,

Figs. 3 and 4; are views of base tensioning mechanism for non-rigid ships,

Fig. 5 is an end view, and

Figs. (3-9 are details.

Figs. 10 and 11 are a side view and plan respectively of a five-fold panorama camera with visual field, I

Figs. 12 and 13 show a five-fold sector camera with visual field in side'view and plan respectively, Y

Fig. 14 is .a diagram of the country to be photographed taken by turning the airship, Fig. 15 is a section through the camera and appertaining devices with stabilizing and adjusting mechanism (mechanical adj ustment) Fig. 16'is a plan of the arrangement shown in Fig. 15,- a

Fig. 17 is a vertical section throughthe arrangement shown in Fig. 15,

Fig. 18 shows the shaft for the directing mechanism (manual and electrical) with band guiding,

Figs. 19 and 20 show details for adjusting the upper end of the sighting spindle,

Fig. 21 is the plan of a (lardan suspension for the camera (electro-mechanical stabilizing and automatic adjustment),

Fig. 22 is a section on the line A-l 3 of Fig. 22,

*i 23 and 24 are section and plan respectively of a camera mechanism engag ing with a Vertical spindle and provided with weight compensating devices,

Fig. 25 shows a snapping-in mechanism of oppositely disposed magnets, the electromagnets being shown to a larger scale,

Fig. 26 illustrates a Cardan arm mounted on a ball (instead of knife-edges),

Fig. 27 is a section and diagrammatic-a1 view through a releasing mechanism durin the horizontal position of the airship axis and vertical position of the camera axes, one pin on each side (left and right) being in the mercury,

Fig, 28 illustrates'a barometer,

Fig. 29 shows the contacts,

Fig. 30 is a diagrammatical view of the current circuit with inclined airship axis (-y), inclination of the left-hand camera on to the west and inclination oi? the right-hand camera [3 to'the cast,

Fig. 31 is a diagrammatical view of the circuits at the moment of exposure,

According to the arrangement shown in Figs. 1 and 2 there is secured to the rigid or unrigid 11-1111 1 a keel in the form of a girder support 2. The cabins 1: and 4.- may be secured either direct to the keel 2 and provided with any known device especially suitable for landing purposes. The cabins may be arranged to be drawn in. This is effected by means of a winding mechanism 6 which may be driven from the gondola by a motor. In order to guard the observation cabins 3 and 4 from shocks, buflers 7 are' providedsimilar to'those used with doorclosers-whwh may engage with their pistons in two cylinders 7 arranged on the keel-frame, which are inter-connected by means of air cocks and piping and operated positively by compressed air.

The weight of the cabins is employed indirectly for tautening the base 8. For this purpose endless wire ropes 9 are guided round the rollers 10, 11 and secured to the cabins 3 and 4, The wire ropes 9 are connected with each other by cross-stays 12 to which is secured a rope 13 which passes through the camera K in the Cardan sus pension. The base 8 itself consists of an invar band which is protected from bending as far as possible by adjustable suspension rollers 16, The base can be altered y means of any suitable device. In order to better distribute the moments of force,

two large transverse tension members 17 may be provided.

The mechanical parallel position of the optical axes of tubes 18, 19 is obtained by a mechanical parallelogram formed by a further band 15 arranged along the keel parallel to the invar base band 8, secured to the suspension point .14 of the left-hand cabin 3 and'terminating on the right-hand cabin after having passed over a roller. Into this hand 15 are inserted the ends of the tubes 18, 19 which lie in the optical axes and which contain the optical sighting devices. These vertical tubes 18, 19 may be adjusted in the vertical position mechanically and in the direction of the base length. To insure the vertical position of the vehicle a number of Renard damping surfaces'or rudders are to be em ployed, but these questions are of aerotechnical and not of surveying-technical nature. The vertical plane in which the photographic apparatus hang is determined by the wire ropes 9 and 13 which carry the whole weight of the cabin and by means of the band 15. y

For ships which are held tautby gas pressure, i. e. by ballonettes, a flexible band is used as illustrated by way of example in Figs. 35. To the hull 28 are secured two inclined struts 29, 30 which are suitably tensioned similar to the wings of a flyingmachine From the front end of the hull awire-rope 31 passes over' the left-hand strut 29, then about 70 metres along the body of the airship, over the right-hand strut 30 and again terminates on the hull. This wire-rope may be brought up to any high tension desired. The gas pressure will support 200 kgs. with ease. Arranged somewhat above this main rope are provided 2 subsidiary ropes 32, 33 so that these three ropes form the edges of a prism.

The cameras K and K are inserted in the holding device 34 for the 'Cardan suspension on the main rope 31. It is preferable to construct the cameras in this case of aluminum. The cameras are adjusted in the present case (Figs. 7, 8, 9) by the .extended vertical bars 35 by the intermediary of the scissors-like device 36. By means of this said device, the vertical guiding bars 35 may be brought into the desired position, by pulling a band 37 or turning a screw 38 attached to the guide-ropes 32, 33.

Two cameras are employed which are exposed simultancoiisly and which are held at a determined distance fromcach' other by means of the base tensioning device 91 'In If these nine-fold, seven-fold or five-fold clination to each other into a single pl1otographic apparatus, Figs. 10-13. In order to obtain as large a visual angle as )ossible, focal distances of 6 or 9 centimetres were employed with the earlier construe tions, but it was found that these focal distances, at heights of from 300-500 metres do not give a picture sufficient in detail to be measured under the comparator micro scope. A further disadvantage of these known constructions lies in the large angle of inclination of the side-cameras to the horizontal. At 45 or even (50 inclination the view in an occupied country is lost, so that photographs for measuring purposes for the preparation of topographical maps is of little value. It has beenshown in conncction with stereo-pliotogramnietrical railway surveys that. the depth etl'ect and clearness of the picture is a function of the focal distance, i. 0. between the focal distance of an objective andthe remoteness of a pull. from which a distance appears measurable by means of the stereoscopic measuring principle, there exists a certain optical relation. As however, the clearness .ot the picture for measuring purposes should 'be the main .t'eature of the photograph on ae-- count of the accuracy of the map to be prepared, then only cameras which have a greati-n- .l'oi-al distance than 20 centimetres can be employed at heights of from 800- 1000 metres. In order now to obviate these F disadvantages of the constructions hitherto employed, panorama and sector cameras of a new construction are necessary. -The tocal distance which is two or eventhree times longer than those hitherto employed necessitates the rejection of the simple sectors (crown cameras) and the adoption of a i'acet construction similar-to the eye. of a fly. Figs. 10 and 11. illustrate a multiplecainera oi th s type. The individual cameras K", 1G, K and K* have the permissible inclination of 30 both in the a: and the y direction,- The objectives are arranged not asin the old construction, but upon a spherical surface 40. The four cameras are built per't'ectly symmetrical and are arranged symmetrically around the centre camera If.

The optical axis of this centrecamera is vertical and the plate consequently horizontal.

' The inclined cameras are arranged diagonally, so that the camera K for example, covers the visual field a, b, 0, (Z, whilst the adjacent. camera K covers the surface a. c, fig. The surfaces overlap by the common area a. d, h. (a (Figs. 10 and 11). The-four surfaces which project beyond the circle 7), [1,37, s serve for ad usting the ad acentphotographs. Sevemfold and nine-fold panorama cameras may be. constructed in lllt Stl lllO manner.

.cabins (Fig. 15).

.This plate 46 is cameras are especially suitable .-f0r topographical panorama photographsQa fiv" old sector camera may Still more advantag, nislv their visual lield is only restricted by the limit of visibility.

The sector cameras likewise. consist of live cameras which, however, all have their objectives in the plane o'l. the paper. The lower three cameras whose total visual field is indie cated by 0, p, Z, in serve, on the forward movement of the airship to photograph successively sections of the country perpendicular to the longitudinal axis of the ship. As the side cameras K', K are inclined at 'i-EtH-to the horizontal, then on the forward movement of the airship quadri-angular sections of country are taken which lie perpendicular to the axis of the airship. If it is desired to work at visual distances exccediiu 5 kilometres, especially for maps-oi small scale, then the centre camera K Fig. 12) is employed in combination with the. two horizontal cameras alone, whereby a stretch of country of 7 0 dicated by the surfaces '0, a, t, o, w, s, '1", '21.. By turning the air ship three times according to the compass (-10" error permissible) the whole periphery is obtained enclosing an all round panorama of about 10 kilometres diameter.

]"n orderto adjust the three photographs with relation to each other, the centre camera is employed which shows the centre surface S three times. This repetition of the nadir district serves for adjusting, for eliminating" centering error and for combining the panorama sections by mcausot the optical comcidence of the picture points.

Increasing thevisual angle 'from 7 0 to picture angle is obtained, in-

llt)

The cameras are arranged within the 4-4 facing each other (Fig. 1) is arranged the fixed seating 45 (Fig. 15) for'the plate 40 which carries the cameras by the intermediary of a circular member 47-. The plate 40 slides in the swallowtail-slide of said circular member in the direction offthe base. provided with an opening which permits of the free movability of further devices which are provided with Cardan suspension. On the plate'46 lies the circular member 47 on the cabin walls 43,

which carries two vertical directing bars 48. These latter, in consequence of the adjusting wires 4-9, 50 and screws 51 and 52 (Fig. 16) assume the positive parallel position of the Y axes of the I two plates. In order to more easily obtain Cardan ring 54. lies the u )permost covering plate 56 which supports the camera below and the remaining instruments above. The plate 56 oscillates on the knife edges 57. The wires 49, 50 are also of invar. this alloy being the least sensitive to temperature diti'erences, Supporting irons 58 with rollers 5!) prevent this wire from sagging.

()n the plate 56 are provided a clock (30 (Fig. 1(5), aperiodic spirit levels 1 arranged Ushape, and an aueroid (32. The clock serves not only for the chronological order of the plate holder numbers. but also for the laterastroiwmieal determination otpole height and azimuth of each individual plate, because the position of the elm-k-hands is also photographed. This elork corresponds to that in the reeonling camera.

()n the plate 56 is arranged a frame. 3 for the recording camera (H. In the frame (33 are provided two round directing discs 98 for the purpose of guiding t he two camera.- parallel in the direction of the longitudinal axis of the airship. Between said discs Us is guided the main rope l3 whicn, on at.

count of its high tension, sharply determines the direction. The recording camera 6-1 contains in its front portion a camera (35 which photographs the position of the oppositely disposed statls 66, (37 "('Fig. 15) arranged perpendicularly to each other, with leveling graduat'ions, at the moment of exposure.

In the lower part of said recording can'rera 641: is arranged a finder (38 which throws on to the observation table 56 the position of the auxiliary instruments, such as levels, clocks, and numbers. -The camera (it also contains an incandescent lamp which flashes on the horizontal position of the ship axis and indicates the moment of exposure.

Into the upper part of the camera Get is inserted the lower end of the telescope 69 contained in the guide spindle 35. The telescope is twice interrupted and contains between the penta prisms 71, 72 and in front of the objective 73 a'prism 7 4 which can be rotated to a certain extent and which therefore inakes the picture vertical. Through mutual position of the optical axes.

In Fig. 17 is illustrated the rear walk-of the camera C3. in which immediately in front.

of the film 76 is rovided a grid 77 which on exposure is pro e'cted on the film and con tains half millimetre graduations.

There is also provided a clock 78 which agrees with the clock 60. The clock 78 is provided with a face of glass and extended hands, and a known numbering device 7 9 is also provided. By means of this recording camera the mutual position of the optical axes of the photographing cameras isascertained and simultaneousl y the difi'erence in height of the photographing cameras. By this means all mathematical data for the position of the two momentary axes of the two cameras K at the moment of exposure with relation to each other may be ascertained. The vertical spindle 35 extends above the telescope into the parallel guiding band 15, on which is provided the swallow-tail adjusting device so (Figs. 1!), 20). By means of the rollers 81, 82 the slides 83, 84 may be adjusted vertically above-each other or forwards and lHH'lUHU'tlS. This displacement is eli'ected from the olraervation.station by means of the cord 85 guided over the roller.

The invar band is tensioned by means of a u eight Ht; whose suspending wire 86' (Fig. 15) is guided over the roller 57. A dynamometer 88 is inserted at the end oi the inrar hand in order to tacilitate the displacement within certain limits and without shocks, and a plate 55) is SO! ured to the cabin wall to catch the weights 86'.

The wire so is guided over the roller which can likewise be rotated. The axis l of this rolleris 'fOlll'lHl as a screw and contained in a tube 92. Into the two slots 93 project pins 94 which on the rotation of the screw 91 move the roller 8? baeluvards and forwards. By this means the-band and indirc tlv the cameras are brought; into the wea'tieal plane of the suspension piston.

The rotation may be eti'ected by means of a cord 5)."), and by this means the-adjustment ot' the two cameras is rendered possible manually.

in order when making photographs to be able to supervise and control the contact or interconnection of the country being surveyed, an inclinometer 96 is provided which is cmmt'erbalanced by the counter-weight 97.

W'hen n'iaking topographical photographs it is not absolutely necessary that the airshi axis be horizontal, because the'appertaining protracting apparatus renders possible the estimation of photographs taken from. unequal heights, but the horizontal position of the airship is desirablefor the stcreo-photogrammetrical normal case which considerably simplifies the measurement of a place. The airship axis can be brought to a horizontal position with sufiicient accuracy by carefully operating the steering members by hand.

In order, however, to make the observer at the cameras independent of the art of navigation, an automatic attainment of the horizontal position is rendered possible by In further prosecuting this idca,.the vertical position of the optical axis of the two cameras is strivon after, so that by means of the co-actiou of the two stabilizing mechanisms of the air ship axes and of the cameras the normal case in obtained and at this moment the shntters of the cameras are simultamously released.

-\Vith the above described Cardan suspension the rings can swing freely through the horizontal position. In order to assure and at the same time to damp these oscillations, :1 device is provided which arrests the (lard-an joint at the moment of the passage through the horizontal, thus acting as a stabilizer upon the oscillatiom As shown in Fig. 22 electromagnets are arranged on the Cardan frames pairwise on the outer and inner frame plates or rings and at such a position with relation to each other that opposite pelts face each other. The direction of flow of current changes according to the inclination and these electromagnets consequently repulse or attract each other.

Fig, 22 shows a section through A-B of Fig, 21. On the actual Cardaii ring .101 there is supported by means of the knife edges 102, 103 the inner Cardan frame 104, upon which the plate 107 which carries the cgmera is supported by the knife edges 105',v 1 6.

These knife edges are arranged as with astronomical 'pendulating apparatus, but can also takethe. form ofballs 154 restingin a socket 155 (Fig. 26). 1 Metal arcs 108 are arranged on the Garden frame 101 (Fig. 22) in'the plane of the knife edges 1.05, 106. These arcs carry the electromagnets 109, 110. In the .innerCardan memher 104 are connected the electromagnets 111 and these electromagnets .in conjunction with magnets 109, 110 efi'ect the quicker agjustment during oscillations ofv the air- S P- I o The electric currents are switched in and out by a suitable device provided on the camera, consisting of inter-communicating tubes 112 filled with mercury, into which said tubes, at their upper ends, there project adjustable pairs of contact pins 113 (1 113 b,

and 114a114b.

In order to render the movement of the mercury surface suit-able for these contact purposes, the tubes are arranged as communicating tubes closed at all ends, and consists preferablyof wood. The upper ends of said tubes are filled with non-conducting petroleum so that the points of contact are exactly-determined and the movement of the pillar of liquid which in spite of the weight of the cameras can. occur may be braked or throttled, as desired. The arrangement shown in Fig. 22 must of course be repeated in .the plane perpendicular to that illustrated, viz, in the plane of the knife edges 102, 103.

If now the contacts 113" and 113", 114 and 114" are adjusted at different heights, then the centre member of the Cardan joint will assume a previously determined inclineol position.

In order to arrest the Cardan rings in the plane of the outer ring 101, further electromagnets are provided which are best seen in Fig. 21. These are the electromagnets which are attached to the individual Cardan frames and to the centre member and project into the free spaces 115, 116 and in consequence of their different windings oppose each other with opposite poles. In the modification illustrated the electromagnets 117, 1183119, 120 are secured to the ring 101, and opposite to them are the magnets on the frame 104, viz, 121', 122, 123, 124. The electromagnets125', 126 127 128 on the same frame 104 serve for the vertical plane of oscillation, and the electromagnets 129 130 131 132 secured on the centre member 107 are arranged alternately to the magnets on the frame 104, viz. 125 126 127 128 The eleetromagnets 117 118 119 120 may be so constructed that they attract movable iron cores 150 on the flow of current which then engage with paraboloid surfaces 151, 152 and, on the interruption of current are withdrawn under the action of springs 153.

The current is switched in so that on the oscillation of the parts 104 and 107 through the plane of the ring 101, the poles of the electromagnets, which at this moment lie opposite to each other, become oppositely magnetized and consequently mutually attract each other. The current is'switched in by the. dipping-in of the contacts 113, 1.13", 114, 114".

The device above described takes effect upon the position on the passage of the Cardan plate through the horizontal or, according to the adjustment until a certain desired angle of elongation is obtained. For adjusting purposes, especially for the exact adjustment of the vertical axis, the spindle 35 extending from the camera K comes into engagement with the cross slide 83 or 84.

As will be seen from Figs. 18, 1,9, 20, these adjusting spindles pass with their upper ends into a cross slide (Figs, 19 and 20) whose screw spindles 81 and 82 are rotated by means of an auxiliary motor 166 which,

may be situated in the cabin, by means of electromechanical del shaft 91 (Fig. 18) so that the directing band 13 is moved to and fro in the Y- direction. This mechanism or its shaft 91 can likewise be driven from an auxiliary motor in the cabin by the intermediary of cord or chain transmission.

The arrangement may, however, be such (Fig. 18) that a small motor 99 is attached direct to the axle. The fixed magnet cores of same are secured to the outer tube so that on rotation the spindle axis rotates and consequently controls the support for the directing band in the vertical direction.

When employing a Cardan suspension of the'type described in airships or flying machines, it is also of importance to counteract movements of weights at any moment. A device especially suitable for this is shown in Figs. 23 and 24.

The shafts 142 which lie in the horizontal plane and extend in the m and 3 direction are driven by small motors 143. On the rotation of the shaft 142 which is threaded at 144, the weights 146 provided thereon and prevented from rotating by guide bars 145 are moved along the threaded spindles. As soon now as any alteration in weight occurs in the Cardan suspension, for instance, if the one plate l'nagazine 147 (Fig. 23) contains more plates than the other magazine 148, then current is switched on to the motor 143 in the manner already employed. The weights 146 in Figs. 23 and 24 must consequently move to the rigl'it or to the left.

In the same way the other weights 146 arranged perpendicular thereto will come into action as soon as necessary.

In order now to produce the normal position in an airship for aero-geodetieal photographs, devices are provided by means of which a simultaneous electrical operation of two photographic apparatus arranged about metres apart is effected with simultaneous automatic adjustment of the airship axis into the horizontal and of the two optical axes into the vertical.

In order to explain the passage of the current, the circuits (and only those in ques tion) are illustrated with deflection to the west (or north) and with inclination to the east (or south).

The current circuits, for the automatic coaetion must be quadrupled with both cameras (for east, west, south and north inclination, Fig. 29.) In practice a number of the wires may be used twice as with opposite defiection the current only reverses its direction along the same path.

The following is the circuit in the lefthand apparatus with the inclination or) against the horizontal: In this case (Fig 30) the right-hand pair of contacts 114: 114, dips into the mercury and closes the circuit. The relay circuit and working circuit must be distinguished from each other:

The relay currenttakes the following path (Fig. 30)

From the terminal of a constant battery, the current flows to the electromagnets 121 of the relay, along the wire 122 through the contact 114 into the mercury, thence through the contact 114 along 123 to the negative pole 124 of the battery.

This current excites the electromagnets of the relay 121 which draws the hammer -25 to the right, whereby the circuit leading from the generator 169 is closed at the contacts 126 and 129*. This service current passes along the wiring 131 into the electromagnets of the outer Cardan ring through the terminal 133, and passes through the wiring 135, 136 into the inner ring 137 o! the suspended camera. The current passes over the wiring 138, 139 along the same path over the rings through the wiring 156, 157, 158, 159, 160. The electromagnets in the Cardan frame are consequently excited and attract or repulse each other according to the winding, so that the rings and the camera strive towards the horizontal. This is rendered easier by the fact that the working current passes along the path 161, 162. 16 3 into the weights 146 which rotate and are moved by electric means, so that said current is guided over 164 and through contact 165 into the electrou'lotor 166 which brings the camera into the vertical position, whereupon the current flows back through the wir ing 167 to the parallel wiring 168 into the generator 169.

lVith the position according to the righthand side, in which the left-hand pair of contacts 113 113", are in the mercury, the relay current COIHIHBHCBS from the pole 1'70. excites the electro-magnet 171, comes over 172 into the contact 113, through the incrcury and the contact 113", over the wiring 173 back to the battery terminal 174.

The service current is closed at 175" by the hammer 126 swinging to the left. service current flows through wiring 175 175, 176, over 160. 159, 157, 156, 139, 128, 137, 135, 134, 133 thus flowing along a path exactly opposite from that described above, then along 177 into the motors 143 and 143" and emerges at 178. The weights 116", H6", are thus moved in the opposite direction from the left-hand position. The current flows over 179 to the machine 166, rotates this in the opposite direction from that on the left-hand side and completes the circuit over 180 through the parallel terminal 181 into the generator 169.

In these two positions the cameras are inclined. Both circuits are available in the east-west direction and perpendicular thercto in the north-south direction.

These circuits differ in no way from those of the left-hand and right-hand positions, as they are perfectly symmetrical and fulfil The the same purpose in the north-south direction.

Other conditions occur when the mercury surface oscillates through the horizontal and comes in contact with the tixed contacts 182, 183, as shown in Figs. 27, 29, 31. In this moment. the current is caused to flow and in the relay the contact carrier 126 is attracted equally by both electromagnets .121, 171 and the service current-is consequently cut out. In order to better retain the neutral position, the hammer is constructed as a piece of a flexible band 126 which bends on attraction. (Fig. 27) and on the interruption of the current immediately swings back in eonsequence of its elasticity. The relay cur rent which passes from the batteries to the.

terminal 199, through 121 and the contacts 11*1 and 113" which dipinto the mercury in the horizontal position, over 171 into the other battery 171), 174 is closed by the wiring 17-1-421- (Fig'. At this moment, however, the relay current which is fed from a small accunmlator batter p'orby the cells 191, 194-, flows also through the contact wiring 182, 18 1, through the incandescent lamp 185 and returns through 183. The lamp 185 now flashes up and at this moment the key 186 may be depressed and the instantaneous shutter-187 is released, whereby the current returns over 188 to 183. This circuit nmst also be guided through the horizontal contacts 182 183 perpendicular to the plane of the paper (Fig. 29).

Fig. 31 shows the whole path of this relay current for the camera release on the horizontal position of the two camera levels.

The course of the relay current is likewise illustrated with the horizontal position of the airship axis (from 183-189), the service current being likewise omitted (this condition that the release of'the two instantaneous shutters 187 and 190 only takes place during the simultaneous horizontal position of the airship axis, may be avoided by tlie direct connection of the contacts 183 with 195 over 191, 192, 193,194).

The relay current flows fromv 183 towards 19l192,'196197, 199-194, 195-189.

At 198 is a further branch and a second key in order to lead the current back partly over 1.99, 185 and 182 to 183 without releasing tlie instantaneous shutters ,and only illaminating the two lamps 185, 199. ()n the depression of the keys 186 or 198, the current flows through the electromagnets of the two instantaneous shutters 187 and 190 and closes both simultaneously, at the same time cutting out the two incandescent lamps.

In order horizontal position within practical permissible limitsof error, or in-o'rder not to exceed same, the contact heads 182, 183. 196, 197, 195 and 189 may have the permissible now to obtain for thephotographs the permissible deviation from the diameter, or the contacts 114: and 11,4, 119

.299 and the rotary pump 202 is held in the central position by the simultaneous attraction of the electromagnets 203, 201 similar to Fig. 29.

its already sta.ted,the two instantaneous shutters may be released independent of the position of the airship axis by directly connecting 189 to 195.

In Fig. 30 the left-hand camera is inclined +11 (to the west) and the right-haml camera (to the east). The air-ship longitudinal axis has'an inclination o1 downwards. 1 The action of the indepelulently operating relay currents and service currents will now immediately begin in order to produce automatically thc'horizonta-l position shown in Fig. 31.

By the inclination to the west, the contacts 111 and 114" (Fig. 30) ,dip into the mercury surface and close the relay current 100, 121,114, 11 9-124. The iron core 121 hecomes magnetized, attracts the hammer 126 which closes the current at 126,129". 7 This current flows over 131, 13 1, into the Cardan magnets 134, 137, then over 198 into the (ardan magnets 139, 159 over 169-161. into the balancing devices 143, then over 165 to the horizont'ahadjusting dynamo 166 and over 167 through the parallel circuit 168 to the generator 169 and over 129 to the point of completion 129". Y These-two currents will continue until the vertical position is" obtained independent of the position of the airship axis and of the other camera.

' The right-hand camera will simultaneously strive to assume the vertical posit-ion. The current path is in this case reversed, but symmetrical. The relay current commences from 174, is closed by the contacts 113, 113

dipping into the mercury, excites the mag- 169, then over 175 to the point of comple-v tion 173*.

The same current employed for producing the horizontal posicircuit may likewise be mathematical position.

'tion of the airship. As thc'ship is inclined downwards by -y, then the contact pins 191, 192 dip into the mercury, excite the electromagents 203 which close the service current at 205, 206. From the generator terminal 207 the current now flows over 208 to the iinishing point 205, 206 towards 209 and here causes the rotation of a rotary pump 202. Vith this position of trim, the pump will force the water towards the raised side. The service current passes from the terminal 210 through 211 and rotates a fan 200 which forces the air to the same side to which the rotary pump forces the water or to the opposite side, as desired. This is etl'ccted in order to damp the oscillations caused by the displacement of the water when effecting the horizontal position. In this case 210 must he connected with 212. The current flows over 213 through the parallel terminal 214 and terminates in the generator 16!).

The service currents continue to act until the axis position has attained the desired or the permissible amplitude or the actual position. It is obvious that the camera release is only etlected in this position of the circuit for the instantaneous shutters as shown in Fig. 31. 9

The last deviations from the vertical position which may be observed in the adjusting telescope can be removed by the simultaneously acting manual devices. Any linal deviations which may occur are shown accuratcly by the photographs of the two recording cameras tS-t whose instantaneous shutters are connected in the circuit 182-489 of the two camera shutters, so that the mathematical data for any final deviations from the normal case are accurately known and can be talcen into consideration when comparing the map, in the appertaining protracting apparatus which is independent of the optical axes in space.

Au aneroid 215 (Figs. 27, 28) can be connected in the circuit, whose circular scale 21; carries a movable vernier 217 which shows the permissible average alteration in the balloon height by its length, so that the hand 218, on attaining the previously adjusted height markcloscs the circuit and releases the shutters.

The two cameras can consequently be re leased after each other in order to make overlapping balloon photographs with longer base and at similar balloon heights when tl'a vellinghorizontally.

The foregoing devices, especially the conneetion between the electrical adjusting mechanism and the manual, is of such construction that the electric current causes the verticality of the two camera axes at least with close approximation to the actual By the manually actuated devices, the deviations observed aero-gtuslctical photographs, the combination with anair vehicle, of a pair of hiaxially arranged cameras spaced aknown distance apart; a tensioned flexible member suspending said cameras from the vehicle; and positive parallel guiding devices eonnccting said cameras.

2. In an apparatus for the production of acro-geodetical photographs, the combination with an air vehicle; of a high tensioned flexible member suspendedirom said .vehiclc; a pair of cameras suspended from said member and each con'iprising a. plurality of long focus cameras having their objectives lying in a common spherical surface; auxiliary instruments associated with the camera: and means for photographieally recording the axial position and the. position of the auxiliary instruments.

3. In an apparatus for the production of acro-gemlctical photographs, the combination with an air vehicle; of a high tensioned tlexible member suspended from said vehicle; a pair of cam-eras suspended from said member and each comprising a plurality of long focus cameras having their objectives lying in a common spherical surface and their axes meeting at the same point at equal angles; auxiliary instruments associ ated with the camera; and means for photo-- graphicallyrecording the axial position and the position of the auxiliary instruments.

4. In an apparatus for the. production oi aero-geodetical photographs, the combination with an air vehicle; of a high tensioned flexible member suspended from said vehicle; a pair of cameras suspended from said member and each comprising a plurality of long focus cameras having their objectives lying in a common spherical surface; auxiliary instruments associated with the camera; means for photographically recordingthe axial position otthe auxiliary instruments; and positive parallel guiding devices interconnecting the cameras.

5. In an apparatus for the production of aero-geodet-ical photographs, the combination with an air vehicle; of a pair of biaxially arranged cameras each comprising a plurality of downwardly pointing eameras, the center camera pointing vertically downwardly and others pointing at a (livergent angle at each side of the center camera, the axes of the center and associatd side cameras lying in the same plane.

loo

lilfi enter lixed member,

6. A process of taking aero-geodetical photographs, consisting in simultaneously steroscopically photographing a central area and adjoining lateral areas; and repeating the process with the axis oi the central area being the same but the exposure being at a difi'erent angle of rotation about said axis and repeating the process until all of the area adjacent to the central area is photographe 7. A process of taking aero-geodetical photographs, consisting in simultaneously steroscopically photographing a central area and adjoining lateral areas; repeating the process with the axis of the central area being the same but the exposure being at a ditl'erent angle of rotation about said axis and repeating the process until all of the area adjacent to the central area is photographed. v v

8. In all apparatus for the production of aero-geodetical photographs, the combination with an air vehicle; of a pair of biaxially arranged cameras; a Gardan suspen sion for each camera, each comprising an an outer oscillating member within the lixed member and an inner oscillating member withinthe outer oscillating member; co-operating electromagnets on each member and the respective surrounding members; a U-tube having mercury therein; contact members at the ends or said tube; and means connecting said contact members to said electromagnet so that when the mercury-contacts the contact members oppositely disposed magnets are excited with opposite polarity.

9. In an apparatus for the production of aero-geodetical photographs, the combination with an air vehicle; of a pair of biaxially arranged cameras; a Oardan suspension for each camera, each comprising an outer fixed member, outer oscillating member Within the fixed member and an inner oscillating member within the outer oscillating member; co-operating electromagnets on each member and the respective surrounding members; a. U-tube having mercury therein; contact members at the ends of said tube; 'means connecting said contact members to said electromagnets so that when the mercury contacts the contact member oppositely disposed magnets are excited with opposite polarity; means for mechanically inter-engaging the iron cores of said magnets during the passage of current and disengaging them when the current ceases.

10. In an apparatus for-the production of aero-geodetical photographs,- the combination with an air vehicle; of a pair of bi-axially arranged cameras; Cardan suspensions supporting the respective cameras on the vehicle and each comprising a base for the adjustment of the camera; shutters on the cameras; communicating tubes located on the cameras and said bases and having mercury therein; adjustable contact pins ar-- ranged in said tubes; and electrical circuit means connected with the contact pins and shutters forming a circuit and thereby 0 ening the shutters, when the camera axes ave attained the vertical position and the vehicle has attained the horizontal position within the desired limits.

11. In an apparatus for the production of aero-geodetical photographs, the combination with an air vehicle; of a pair of biaxially arranged cameras; Gardan suspensions supporting the respective cameras on the vehicle and each comprising a central member and a base for the adjustmentj of the camera; shutters on the cameras; communicating tubes located on the cameras and said bases and having mercury therein; adjustable contact pins arranged in said tubes; and electrical circuit means connected with the contact pins, said central member and shutters forming a circuit and thereby opening the shutters, and braking or adjusting the central member when the camera axes have attained the vertical position and the vehicle has attained the horizontal position within the desired limits.

12. In an apparatus for the production of aero-geodetical photographs, the comin; adjustable contact pins arranged in said tubes; electrical circuit means connected with the contact pins, said central member and shutters forming a .circuit and thereby opening the shutters, and braking or adjusting the central member when the- )camera axes have attained the vertical position and the vehicle has attained the horizontal position within the desired limits; and a lamp included in said circuit means and adapted to be lighted thereby whenthe requiredposition of the cameras. and air vehicle is arranged. v

13. In an apparatus for the production of aero-geodetical photographs, the combination with an air vehicle; of a pair of bi-axially arranged cameras; Oardan suspensions supporting the respective cameras on the vehicle and each comprising a central member and a base for the adjustment of the camera; shutters on the cameras; communicating tubes located and said bases and having mercury therein; adjustable contact pins arranged in saidtubes; electrical circuit means connected on the' cameras 

